Improvement in construction of bridges



UNITEDSrArEs PATENT EEICE.

c. snALEE sMIrH,c..n. LATEOEE, AND FREDERICK n. SMITH, or EALTI.

MOEE, MARYLAND.

IMPROVEMENT IN cNsTRucTloN oF BRIDGES.

To whom it may concern.'

Beit known that we, G. SHALER SMITH, C. Y

H. LArRoBE, and FREDERICK ELSMITH, of

Baltimore, county of Baltimore, and State of Maryland, have invented certain new and useful Improvements in Bridges; and we hereby declare the following to be a full, clear,

and exact description of the same, reference being had to the accompanying drawing, in which- Figure 1 is a side elevation of 'a trestlebridge made in accordance with our invention.

` j Fig. `2 is a transverse section of the same.

Figs. 3, 4, 5, and 6 are views on Aan enlarged scale of detached parts. f

Our invention may be stated to consist in, first, the use, in a system of wrought-iron piers or continuous trestle, composed of wroughtiron columns combined with cast-iron jointboxes interposed between and forming the bearings of the sections of the columns, as hereinafter described, of longitudinal diagonal ties which shall connect the joints of any one tier with those of another tier or withthe caps o'r feet of the columns forming the piers, and the attachment of these ties directly to' the columns themselves or to the cast joints, caps, or feet, or to the longitudinal struts, as may be best in. dierent locations; second, the combination, with the piers and systemef longitudinal diagonal `ties connecting the same, of the wooden chord-sticks and longitudinal system of wooden struts for supporting the roadway and stiiening the piers; third, the construction of the cast-iron post-caps, foot-boxes, and joint-boxes for the wrought-iron columns, substantially` as hereinafter shown and described; fourth, the combination of a series of independent or isolated bridge-piers, formed, as described, with an intermediate span or spans of truss connecting the same, substantially as hereinafter set forth, fifth, uniting the longitudinal diagonal ties with the columns or boxes of said columns by means of a yoke and screwnut attachment, such as hereinafter described, so as to admit of the ready adjustment of said ties; sixth, a system of continuous trestle for bridges in which the longitudinal diagonal rods or ties which conneet the caps `and feet orjoints of the columns are combined with intermediate spans of truss extending between said columns.

stand and use our invention, we will now proceed to describe the manner in which the same is or may be carried into effect, by reference to accompanying drawing.

1. The onstructon of the Piers.

' These parts are formed of columns or shafts of wrought iron or steel of any form of section, which, as shown in Fig. 6, fit over tenons formed on the cast-iron foot-boxes F. These footboxes are bolted or otherwise suitably anchored to masonry, and to them are pinned or pivoted the straps or yokes which receive the lower ends of the longitudinal diagonal ties 4. Running through the castings and secured thereto by bolts are `the transverse struts S3, formed each of two channel-bars or their equivalents for the purpose, between which the lateral ties 2 are hung. The upper end of each column fits over a tenon formed j on the cast-iron post-cap C, Fig. 4, this cap being adapted to receive and hold the chord sticks, the crossstruts, the truss-chains, and the longitudinal diagonal ties. The chordsticks are framed in pairs to the cap, one on each side of the rib that extends'across its top, and on each side of which 'are placed theplates or bars which run through the cap and form the jaws between which the longitudinal diagonal ties take hold of the cap. These bars are held in place by the pin upon which the truss-chains are hung, the pin passing through the hole formed for its reception in the cap, as represented in Fig. 4.'

The :construction and arrangement of the cross-strut S1 in nowise diifers from that of the strut S3 already mentioned. Thelateral ties l also take hold of the cap in the manner a1- readf described with reference to the lateral ties i To unite the column with its cap and foot, all that is required is to slip its ends over the tenons formed on the foot-box and cap, so thatA the pier can be set up with great ease and expedition. Y v Y To construct the piers of considerable height we form them in tiers or stories, and to this 'end To enable others skilled in the art to undery we make .use ot' cast-iron joint-boxes, such as represented in Fig. 5. This joint-box, which is interposed between and forms the bearing for the contiguous ends of the sections to be united, has a tenen on each end, over which ts the upper end of the lower section and the lower end ofthe upper section, to be joined in one continuous pier; as, for instance, in Fig. l the center piers are made in three stories or tiers, A B, B C, C D, thus necessitating the employment of a foot-box, cap, and two joint boxes. The lower column O D, tits over the tenon of foot-box and the lower tenon of the first jointbox. The middle column B C ts over the upper tenon of the first, and the lower tenon ofthe second joint-box, and so on.

This method of uniting the sections combines in itself 'strength and ease in fitting the parts together. The contiguous ends ot' the wrought-iron sections, united by the jointbox es, have no contact with each other, but take a direct bearing on the boxes themselves, and the structure can be set up with great rapidity and facility.

The cross-strut S2, made of channel-bars, is secured in the joint-box, in the manner already indicated, with reference to the struts S1 S3, and from between the channel-bars the lateral ties l 2 extend in the usual manner.

The two longitudinal tie rods or stays 4 which meet or cross each other on the same side of the joint-box, have their straps hung upon the same pin, as shown in the figure. le stii'en the piers at their joints by means of a system of longitudinal struts, X, which are anchored or abut against masonry or its equivalent at each end of the bridge, and lit into the joint-boxes, as seen in Fig. 5. 1n a continuous trestle-work we prefer, and, in fact, nd it quite necessary, to make these struts, as well as the chord-sticks, of wood, in order to prevent the contraction and expansion consequent upon the employment of an iron-strut system.

In illustration of our invention we have described the method we prefer of constructing the cast-iron caps, feet, and joints, and of uniting them with their wrought-iron columns. The construction of these parts may, however, be varied to a great extent according as circum- -stances require and, so far as the method of uniting the parts is concerned, the columns may it over the caps, feet, and joints, or the latter may t over the former, or the two may be riveted or bolted together, as may be found necessary in using different sections of columns.

In all cases, however, we obtain piers formed of shafts or columns of wrought-iron or steel, with feet, caps, and joints, where the same are employed, of cast-iron.

l 2. The Longitudinal Diagonal Tie System.

The manner in which these ties 3 4. can be usedis shown in diagram Jn Fig. 1. The upper end of one stay, in this instance, is anchored t0 the top of one kpier or pst,-and thence it extends diagonally downward, and is anchored to the foot of the second, third, or further pier beyond, passing through and being united with the joint-boxes of the intermediate co1- umns. v

The manner in which the tics 4 are united with the columns which theyintersect is shown clearly in Fig. 5. Their ends pass through yokes or jaws pivoted to the boxes, and are there held by means of screw-nuts, by which the ties can be tightened and readily adjustl ed, this being a matter of some importance, as in bridges built upon this system the metal is affected bythe variation in temperature, and the parts require, therefore, to be adjusted to compensate for whatever contraction or expansion may take place. By this means, although less material is employed in the tension members, the piers are nevertheless just as well or even better adapted to resist the strain than with the ordinary system of bracing, which will require a much greater amount of material. The whole structure, in` fact,fis united in one continuous system, .each part supporting and upholding the other.

This system of tie-rods is represented as continuous from the cap of one column to the base of another; but it can also be used withjust as good eft'ect to connect the joints of one tier with those of another tier, or with the caps or feet of the columns forming the piers; and while we nd it convenient and best on many accounts to attach the ties to the feet, caps, and joint-boxes in the manner already described, yet they maybe also attached directly to the columns themselves, or to the longitudinal struts, as may be best in different locations, without departing from the principle of our invention.

The mode above described is adapted more particularly to the crossing of dry ravines or valleys where there is no stream 'of any considerable size to be bridged 5 but in case a large body of water must be spanned, or other circumstances make it inconvenient or impracticable to employ a continuous trestle-work, we contemplate the construction of independent piers upon the same general plan, which can be connected by one or more channelspans. For instance, suppose that the three center bents of the structure, shown in Fig. 1, were removed, thus leaving the independent piers 5 between these two piers a channel-span, composed of any suitable form of truss, should be introduced, and, by counterbracin g the end bents of the two piers, a perfectly safe and stron g bridge would be produced.

When the piers are thus constructed itis notnecessary that thelongitudinal stays should be anchored to the foot of any one column, but they may extend from the cap of one post to any point on the second or further post beyond intermediate between the cap and base, being united, of course, withthe intermediate column or columns, as above described,

In the bridge represented in illustration of our invention, the piers or columns are set at such a distance as to require the use of a truss; but ofcourse the posts can be set at anyrequired distance'apart, so as to dispense, if need be, with the truss.

The combined use of the intermediate spans and longitudinal ties withthe piers, as shown in Fig. `-1, isflhowever, productive of great advantage; for a strong andvdurable structure isobtained, while at the same time we are enabled to set the posts or columns at a greater distance apart than has heretofore been found practicable; and, so far as this portion of our invention is concerned, the particular construction of the columns or posts is immaterial, thoughwe prefer the construction hereinbev fore described. In place-0f the channel-bars or iron of equivalent form inserted in the boxes or caps, and used for the cross-struts, we have employed small columns which fit over tenons cast on* the sides of the joint boxes, footboxes, or caps with which the struts require to be connected.

Having now described our invention, and the manner in which the same is or may be carried into elect, we would say that we do not here claim the combination of wroughtiron column with cast-iron caps, feet, or joints,

when used to form either independent piers or for the column-sections,of longitudinal diagonal ties, connecting, substantially in the manner specified, the joints of any one tier with those of another tier, or with the caps or feet of the columns, for the purposes set forth.

2. The combination, with the piers and system of longitudinal diagonal ties'connectingv the same, of the wooden chordsticks and longitudinal system of wooden struts for supporting the roadway and stiffening the piers.

3. The construction of the cast-iron posts, caps, foot-boxes, and joint-boxes, substantially as shown and described.

4. The combination of a series of independ ent or isolated bridge-piers, formed, as described, with an intermediate span or spans of truss connecting the same, substantially as set forth.

5. Uniting the longitudinal diagonal ties with the columns or boxes of said columns by means of the yoke and screwinut attachment, substantially as shown and described, so as to admitof the ready adjustment of said ties, for the purposes stated.

6. A system of continuous trestle for bridges in which the longitudinal diagonal rods or ties which connect the caps and feet or joints of the columns are combined with intermediate spans of truss extending between said col umns, substantially as shown and set forth.

In testimony whereof we have signed our names to this specification before two subscribing witnesses.

C. SGHALER SMITH.

Witnesses as to C. SHALER SMITH:

Jos. H. ALEXANDER, MORGAN E. PRESTON.

C. H. vLATBOBE. FREDERICK H. SMITH. Witnesses: MICHAEL H. CARROLL, NEWTON M. GRAY. 

